Harry Potter and the Order of the Phoenix (JK Rowlings) is good. I have a few minor quibbles (Umbridge isn't very politically savvy, Hagrid ought to be deadlier when he's mad, the Death Eaters are wayyyy out of practice at fighting), but set these aside. Harry's reluctance to confide in adults is even more pronounced as his teenage years advance, which is both insanely stupid in his circumstances and annoyingly accurate (three teenagers so far, two in waiting). As usual, Harry is not a solitary hero, though for a while you wonder if he will manage to keep any friends. Go read it. (You have to have read the other 4 books first, of course.)

The best children's books can be enjoyed by adults: Alice in Wonderland, Goodnight Moon, The Wind in the Willows, Gulliver's Travels, the old folk/fairy tales, and so on. (In fact, some were written for adults.) If you haven't read these, by all means do: they are good fun. (Goodnight Moon is a short and very fine poem: I wish I could write like that.) Likewise Harry Potter: I'll take that over The Accidental Tourist any day. ~